def __init__(self, key=None, value=None, p=None):
self._key = None<EOL>self._value = None<EOL>self._personalization = None<EOL>if key is not None:<EOL><INDENT>self.key = key<EOL><DEDENT>if value is not None:<EOL><INDENT>self.value = value<EOL><DEDENT>if p is not None:<EOL><INDENT>self.personalization = p<EOL><DEDENT>
Create a Substitution with the given key and value.

        :param key: Text to be replaced with "value" param
        :type key: string, optional
        :param value: Value to substitute into email
        :type value: string, optional
        :param name: p is the Personalization object or Personalization object
                     index
        :type name: Personalization, integer, optional