def __init__(self, key_schema, value_schema):
if not isinstance(key_schema, Schema):<EOL><INDENT>raise securesystemslib.exceptions.FormatError('<STR_LIT>'<EOL>'<STR_LIT>' + repr(key_schema))<EOL><DEDENT>if not isinstance(value_schema, Schema):<EOL><INDENT>raise securesystemslib.exceptions.FormatError('<STR_LIT>'<EOL>'<STR_LIT>' + repr(value_schema))<EOL><DEDENT>self._key_schema = key_schema<EOL>self._value_schema = value_schema<EOL>
<Purpose>
  Create a new DictOf schema.

<Arguments>
  key_schema:  The dictionary's key.
  value_schema: The dictionary's value.