Pattern: Missing use of each_key/each_value
Issue: -
This rule checks for uses of each_key and each_value Hash methods.
Note: If you have an array of two-element arrays, you can put parentheses around the block arguments to indicate that you're not working with a hash, and suppress RuboCop offenses.
# bad
hash.keys.each { |k| p k }
hash.values.each { |v| p v }
# good
hash.each_key { |k| p k }
hash.each_value { |v| p v }