'Extract values from a dictionary and return a new dictionary with
extracted values.
:param obj: Dictionary to extract values from.
:type obj: ``dict``
:param keys: Keys to extract.
:type keys: ``list``
:return: Dictionary with extracted values.
:rtype: ``dict``'

def _extract_values(self, obj, keys):

    result = {}
    for key in keys:
        result[key] = obj[key]
    return result
