diff --git a/boa/blockchain/vm/System/ExecutionEngine.py b/boa/blockchain/vm/System/ExecutionEngine.py
index f80e32a34..d14e5db9c 100644
--- a/boa/blockchain/vm/System/ExecutionEngine.py
+++ b/boa/blockchain/vm/System/ExecutionEngine.py
@@ -4,10 +4,17 @@ class ExecutionEngine():
     pass
 
 
-#def GetScriptContainer():
-#    pass
+def GetScriptContainer():
+    pass
+
+
+def GetExecutingScriptHash():
+    pass
+
 
+def GetCallingScriptHash():
+    pass
 
-#def GetExecutingScriptHash():
-#    pass
 
+def GetEntryScriptHash():
+    pass
\ No newline at end of file
diff --git a/boa/code/builtins.py b/boa/code/builtins.py
index 0c50db4ae..4efd34256 100644
--- a/boa/code/builtins.py
+++ b/boa/code/builtins.py
@@ -1,4 +1,8 @@
 
+
+
+
+
 class list(list):
 
     def __init__(self, length=0):
@@ -86,6 +90,36 @@ def __setitem__(self, *args, **kwargs):  # real signature unknown
         pass
 
 
+# @TODO this currently reverses the order of str1 and str2
+def concat(str1, str2):
+    """
+     range(str1, str2) -> str object
+
+     Return a string that is the concatenation of the two arguments
+     """
+    pass
+
+
+# @TODO this currently does not work
+#def substr(source,start_index, count):
+#    """
+#    substr(source, start_index, count) -> list object
+#
+#    Return a subset of a string `source`, starting at `start_index` and
+#    of length `count`
+#    """
+#    pass
+
+
+# @TODO this currently does not work
+#def take(source, count):
+#    """
+#    take(source, count) -> list object
+#
+#    Return a subset of a string or list `source`, starting
+#    at index 0 and of length `count`
+#    """
+#    pass
 
 
 def range(start, stop):
diff --git a/boa/code/token.py b/boa/code/token.py
index 079fdcf1b..60bc826ac 100644
--- a/boa/code/token.py
+++ b/boa/code/token.py
@@ -802,7 +802,7 @@ def convert_method_call(self, pytoken):
 
     def is_op_call(self, op):
 
-        if op in ['len','abs','min','max',]:
+        if op in ['len','abs','min','max','concat','substr','take']:
             return True
         return False
 
@@ -816,6 +816,12 @@ def convert_op_call(self, op, pytoken=None):
             return self.convert1(VMOp.MIN,pytoken)
         elif op == 'max':
             return self.convert1(VMOp.MAX,pytoken)
+        elif op == 'concat':
+            return self.convert1(VMOp.CAT,pytoken)
+        elif op == 'substr':
+            return self.convert1(VMOp.SUBSTR,pytoken)
+        elif op == 'take':
+            return self.convert1(VMOp.LEFT,pytoken)
         return None
 
     def is_notify_call(self, op):
diff --git a/boa/tests/src/ConcatTest.py b/boa/tests/src/ConcatTest.py
new file mode 100644
index 000000000..409515523
--- /dev/null
+++ b/boa/tests/src/ConcatTest.py
@@ -0,0 +1,13 @@
+from boa.code.builtins import concat
+
+def Main():
+
+    str1 = 'hello'
+    str2 = 'world'
+
+    str3 = concat(str1,str2)
+
+    #this ends up being 'worldhello'
+    #need to reverse the parameters...
+
+    return str3
\ No newline at end of file