diff --git a/netcompare/check_type.py b/netcompare/check_type.py
index 6e101d1..dee3b6b 100644
--- a/netcompare/check_type.py
+++ b/netcompare/check_type.py
@@ -1,5 +1,5 @@
 """CheckType Implementation."""
-from typing import Mapping, Tuple, Union, List
+from typing import Mapping, Tuple, List, Dict, Any
 from .evaluator import diff_generator, parameter_evaluator
 from .runner import extract_values_from_output
 
@@ -12,7 +12,11 @@ def __init__(self, *args):
 
     @staticmethod
     def init(*args):
-        """Factory pattern to get the appropiate CheckType implementation."""
+        """Factory pattern to get the appropriate CheckType implementation.
+
+        Args:
+            *args: Variable length argument list.
+        """
         check_type = args[0]
         if check_type == "exact_match":
             return ExactMatchType(*args)
@@ -24,15 +28,21 @@ def init(*args):
         raise NotImplementedError
 
     @staticmethod
-    def get_value(value: Mapping, path: Mapping, exclude: List = None) -> Union[Mapping, List, int, str, bool]:
+    def get_value(output: Mapping, path: str, exclude: List = None) -> Any:
         """Return the value contained into a Mapping for a defined path."""
-        return extract_values_from_output(value, path, exclude)
+        return extract_values_from_output(output, path, exclude)
 
-    # TODO: Refine this typing
-    def evaluate(self, reference_value: Mapping, value_to_compare: Mapping) -> Tuple[Mapping, bool]:
+    def evaluate(self, reference_value: Any, value_to_compare: Any) -> Tuple[Dict, bool]:
         """Return the result of the evaluation and a boolean True if it passes it or False otherwise.
 
         This method is the one that each CheckType has to implement.
+
+        Args:
+            reference_value: Can be any structured data or just a simple value.
+            value_to_compare: Similar value as above to perform comparison.
+
+        Returns:
+            tuple: Dictionary representing check result, bool indicating if differences are found.
         """
         raise NotImplementedError
 
@@ -40,7 +50,7 @@ def evaluate(self, reference_value: Mapping, value_to_compare: Mapping) -> Tuple
 class ExactMatchType(CheckType):
     """Exact Match class docstring."""
 
-    def evaluate(self, reference_value: Mapping, value_to_compare: Mapping) -> Tuple[Mapping, bool]:
+    def evaluate(self, reference_value: Any, value_to_compare: Any) -> Tuple[Dict, bool]:
         """Returns the difference between values and the boolean."""
         diff = diff_generator(reference_value, value_to_compare)
         return diff, not diff
@@ -50,7 +60,7 @@ class ToleranceType(CheckType):
     """Tolerance class docstring."""
 
     def __init__(self, *args):
-        """Tollerance init method."""
+        """Tolerance init method."""
         try:
             tolerance = args[1]
         except IndexError as error:
@@ -59,13 +69,13 @@ def __init__(self, *args):
         self.tolerance_factor = float(tolerance) / 100
         super().__init__()
 
-    def evaluate(self, reference_value: Mapping, value_to_compare: Mapping) -> Tuple[Mapping, bool]:
-        """Returns the difference between values and the boolean."""
+    def evaluate(self, reference_value: Mapping, value_to_compare: Mapping) -> Tuple[Dict, bool]:
+        """Returns the difference between values and the boolean. Overwrites method in base class."""
         diff = diff_generator(reference_value, value_to_compare)
         diff = self._get_outliers(diff)
         return diff, not diff
 
-    def _get_outliers(self, diff: Mapping) -> Mapping:
+    def _get_outliers(self, diff: Mapping) -> Dict:
         """Return a mapping of values outside the tolerance threshold."""
         result = {
             key: {sub_key: values for sub_key, values in obj.items() if not self._within_tolerance(**values)}
@@ -82,7 +92,7 @@ def _within_tolerance(self, *, old_value: float, new_value: float) -> bool:
 class ParameterMatchType(CheckType):
     """Parameter Match class implementation."""
 
-    def evaluate(self, reference_value: Mapping, value_to_compare: Mapping) -> Tuple[Mapping, bool]:
+    def evaluate(self, reference_value: Mapping, value_to_compare: Mapping) -> Tuple[Dict, bool]:
         """Parameter Match evaluator implementation."""
         try:
             parameter = value_to_compare[1]
diff --git a/netcompare/evaluator.py b/netcompare/evaluator.py
index af7ce6b..a81ec95 100644
--- a/netcompare/evaluator.py
+++ b/netcompare/evaluator.py
@@ -3,15 +3,23 @@
 import sys
 from collections import defaultdict
 from functools import partial
-from typing import Mapping, List, Dict
+from typing import Any, Mapping, Dict, List
 from deepdiff import DeepDiff
 
 
 sys.path.append(".")
 
 
-def diff_generator(pre_result: Mapping, post_result: Mapping) -> Dict:
-    """Generates diff between pre and post data based on check definition."""
+def diff_generator(pre_result: Any, post_result: Any) -> Dict:
+    """Generates diff between pre and post data based on check definition.
+
+    Args:
+        pre_result: dataset to compare
+        post_result: dataset to compare
+
+    Returns:
+        differences between two datasets
+    """
     diff_result = DeepDiff(pre_result, post_result)
 
     result = diff_result.get("values_changed", {})
@@ -27,13 +35,20 @@ def diff_generator(pre_result: Mapping, post_result: Mapping) -> Dict:
     return result
 
 
-def get_diff_iterables_items(diff_result: Mapping) -> Mapping:
-    """Return a dict with new and missing values where the values are in a list."""
-    # DeepDiff iterable_items are returned when the source data is a list
-    # and provided in the format: "root['Ethernet3'][1]"
-    # or more generically: root['KEY']['KEY']['KEY']...[numeric_index]
-    # where the KEYs are dict keys within the original object
-    # and the "[index]" is appended to indicate the position within the list.
+def get_diff_iterables_items(diff_result: Mapping) -> Dict:
+    """Helper function for diff_generator to postprocess changes reported by DeepDiff for iterables.
+
+    DeepDiff iterable_items are returned when the source data is a list
+    and provided in the format: "root['Ethernet3'][1]"
+    or more generically: root['KEY']['KEY']['KEY']...[numeric_index]
+    where the KEYs are dict keys within the original object
+    and the "[index]" is appended to indicate the position within the list.
+
+    Args:
+        diff_result: iterable comparison result from DeepDiff
+    Returns:
+        Return a dict with new and missing values where the values are in a list.
+    """
     get_dict_keys = re.compile(r"^root((\['\w.*'\])+)\[\d+\]$")
 
     defaultdict_list = partial(defaultdict, list)
@@ -54,12 +69,20 @@ def get_diff_iterables_items(diff_result: Mapping) -> Mapping:
     return result
 
 
-def fix_deepdiff_key_names(obj: Mapping) -> Mapping:
-    """Return a dict based on the provided dict object where the brackets and quotes are removed from the string."""
+def fix_deepdiff_key_names(obj: Mapping) -> Dict:
+    """Return a dict based on the provided dict object where the brackets and quotes are removed from the string.
+
+    Args:
+        obj: Example: {"root[3]['7.7.7.7']['is_enabled']": {'new_value': False, 'old_value': True},
+                       "root[3]['7.7.7.7']['is_up']": {'new_value': False, 'old_value': True}}
+
+    Returns:
+        aggregated output Example: {'7.7.7.7': {'is_enabled': {'new_value': False, 'old_value': True},
+                                                'is_up': {'new_value': False, 'old_value': True}}}
+    """
     pattern = r"'([A-Za-z0-9_\./\\-]*)'"
 
     result = {}
-    # root[2]['10.64.207.255']['accepted_prefixes']
     for key, value in obj.items():
         key_parts = re.findall(pattern, key)
         partial_res = group_value(key_parts, value)
@@ -67,14 +90,14 @@ def fix_deepdiff_key_names(obj: Mapping) -> Mapping:
     return result
 
 
-def group_value(tree_list: List, value: Mapping) -> Mapping:
+def group_value(tree_list: List, value: Dict) -> Dict:
     """Build dictionary based on value's key and reference key."""
     if tree_list:
         return {tree_list[0]: group_value(tree_list[1:], value)}
     return value
 
 
-def dict_merger(original_dict: Mapping, merged_dict: Mapping):
+def dict_merger(original_dict: Dict, merged_dict: Dict):
     """Merge dictionaries to build final result."""
     for key in merged_dict.keys():
         if key in original_dict and isinstance(original_dict[key], dict) and isinstance(merged_dict[key], dict):
@@ -83,7 +106,7 @@ def dict_merger(original_dict: Mapping, merged_dict: Mapping):
             original_dict[key] = merged_dict[key]
 
 
-def parameter_evaluator(values: Mapping, parameter: Mapping) -> Mapping:
+def parameter_evaluator(values: Mapping, parameter: Mapping) -> Dict:
     """Parameter Match evaluator engine."""
     # value: [{'7.7.7.7': {'peerAddress': '7.7.7.7', 'localAsn': '65130.1100', 'linkType': 'external'}}]
     # parameter: {'localAsn': '65130.1100', 'linkType': 'external'}
diff --git a/netcompare/runner.py b/netcompare/runner.py
index 8bdec1d..d93fa7f 100644
--- a/netcompare/runner.py
+++ b/netcompare/runner.py
@@ -1,6 +1,6 @@
 """Library wrapper for output parsing."""
 import re
-from typing import Mapping, List, Union
+from typing import Mapping, List, Union, Any
 import jmespath
 from .utils.jmspath_parsers import jmspath_value_parser, jmspath_refkey_parser
 from .utils.filter_parsers import exclude_filter
@@ -8,42 +8,49 @@
 from .utils.flatten import flatten_list
 
 
-def extract_values_from_output(value: Mapping, path: Mapping, exclude: List) -> Union[Mapping, List, int, str, bool]:
-    """Return data from output depending on the check path. See unit text for complete example."""
-    # Get the wanted values to be evaluated if jmspath expression is defined, otherwise
-    # use the entire output if jmespath is not defined in check. This cover the "raw" diff type.
-    if path and not exclude:
-        wanted_value = jmespath.search(jmspath_value_parser(path), value)
-
-    elif path and exclude:
-        wanted_value = jmespath.search(jmspath_value_parser(path), value)
-        exclude_filter(wanted_value, exclude)
-    elif not path and exclude:
-        exclude_filter(value, exclude)
-        return value
-
-    # data type check
-    if path:
-        if not any(isinstance(i, list) for i in wanted_value):
-            return wanted_value
-
-        for element in wanted_value:
-            for item in element:
-                if isinstance(item, dict):
-                    raise TypeError(
-                        f'Must be list of lists i.e. [["Idle", 75759616], ["Idle", 75759620]]. You have {wanted_value}\'.'
-                    )
-                if isinstance(item, list):
-                    wanted_value = flatten_list(wanted_value)
-                    break
-
-            paired_key_value = associate_key_of_my_value(jmspath_value_parser(path), wanted_value)
-    else:
-        paired_key_value = value
-
-    if path and re.search(r"\$.*\$", path):
-        wanted_reference_keys = jmespath.search(jmspath_refkey_parser(path), value)
+def extract_values_from_output(output: Union[Mapping, List], path: str, exclude: List = None) -> Any:
+    """Return data from output depending on the check path. See unit test for complete example.
+
+    Get the wanted values to be evaluated if JMESPath expression is defined,
+    otherwise use the entire output if jmespath is not defined in check. This covers the "raw" diff type.
+    Exclude data not desired to compare.
+
+    Notes:
+        https://jmespath.org/ shows how JMESPath works.
+
+    Args:
+        output: json data structure
+        path: JMESPath to extract specific values
+        exclude: list of keys to exclude
+    Returns:
+        Evaluated data, may be anything depending on JMESPath used.
+    """
+    if exclude:
+        exclude_filter(output, exclude)  # exclude unwanted elements
+
+    if not path:
+        return output  # return if path is not specified
+
+    values = jmespath.search(jmspath_value_parser(path), output)
+
+    if not any(isinstance(i, list) for i in values):  # check for multi-nested lists if not found return here
+        return values
+
+    for element in values:  # process elements to check is lists should be flatten
+        for item in element:
+            if isinstance(item, dict):  # raise if there is a dict, path must be more specific to extract data
+                raise TypeError(
+                    f'Must be list of lists i.e. [["Idle", 75759616], ["Idle", 75759620]].' f"You have {values}'."
+                )
+            if isinstance(item, list):
+                values = flatten_list(values)  # flatten list and rewrite values
+                break  # items are the same, need to check only first to see if this is a nested list
+
+    paired_key_value = associate_key_of_my_value(jmspath_value_parser(path), values)
+
+    if re.search(r"\$.*\$", path):  # normalize
+        wanted_reference_keys = jmespath.search(jmspath_refkey_parser(path), output)
         list_of_reference_keys = keys_cleaner(wanted_reference_keys)
         return keys_values_zipper(list_of_reference_keys, paired_key_value)
 
-    return paired_key_value
+    return values
diff --git a/netcompare/utils/jmspath_parsers.py b/netcompare/utils/jmspath_parsers.py
index 4204e2c..31863f1 100644
--- a/netcompare/utils/jmspath_parsers.py
+++ b/netcompare/utils/jmspath_parsers.py
@@ -4,7 +4,7 @@
 
 def jmspath_value_parser(path: str):
     """
-    Get the JMSPath  value path from 'path'.
+    Get the JMSPath value path from 'path'.
 
     Args:
         path: "result[0].vrfs.default.peerList[*].[$peerAddress$,prefixesReceived]"
diff --git a/netcompare/utils/refkey.py b/netcompare/utils/refkey.py
index 4ce3ad4..923af96 100644
--- a/netcompare/utils/refkey.py
+++ b/netcompare/utils/refkey.py
@@ -1,8 +1,8 @@
 """Reference key utilities."""
-from typing import Mapping, List
+from typing import Mapping, List, Optional
 
 
-def keys_cleaner(wanted_reference_keys: Mapping) -> List[Mapping]:
+def keys_cleaner(wanted_reference_keys: Mapping) -> Optional[List[Mapping]]:
     """Get every required reference key from output."""
     if isinstance(wanted_reference_keys, list):
         return wanted_reference_keys
@@ -52,13 +52,11 @@ def associate_key_of_my_value(paths: str, wanted_value: List) -> List:
     final_list = []
 
     for items in wanted_value:
-        temp_dict = {}
-
         if len(items) != len(my_key_value_list):
             raise ValueError("Key's value len != from value len")
 
-        for my_index, my_value in enumerate(items):
-            temp_dict.update({my_key_value_list[my_index]: my_value})
+        temp_dict = {my_key_value_list[my_index]: my_value for my_index, my_value in enumerate(items)}
+
         final_list.append(temp_dict)
 
     return final_list