def lookup_developer_identity(IdentityPoolId=None, IdentityId=None,
    DeveloperUserIdentifier=None, MaxResults=None, NextToken=None):
    """
    Retrieves the IdentityID associated with a DeveloperUserIdentifier or the list of DeveloperUserIdentifier s associated with an IdentityId for an existing identity. Either IdentityID or DeveloperUserIdentifier must not be null. If you supply only one of these values, the other value will be searched in the database and returned as a part of the response. If you supply both, DeveloperUserIdentifier will be matched against IdentityID . If the values are verified against the database, the response returns both values and is the same as the request. Otherwise a ResourceConflictException is thrown.
    You must use AWS Developer credentials to call this API.
    See also: AWS API Documentation
    
    
    :example: response = client.lookup_developer_identity(
        IdentityPoolId='string',
        IdentityId='string',
        DeveloperUserIdentifier='string',
        MaxResults=123,
        NextToken='string'
    )
    
    
    :type IdentityPoolId: string
    :param IdentityPoolId: [REQUIRED]
            An identity pool ID in the format REGION:GUID.
            

    :type IdentityId: string
    :param IdentityId: A unique identifier in the format REGION:GUID.

    :type DeveloperUserIdentifier: string
    :param DeveloperUserIdentifier: A unique ID used by your backend authentication process to identify a user. Typically, a developer identity provider would issue many developer user identifiers, in keeping with the number of users.

    :type MaxResults: integer
    :param MaxResults: The maximum number of identities to return.

    :type NextToken: string
    :param NextToken: A pagination token. The first call you make will have NextToken set to null. After that the service will return NextToken values as needed. For example, let's say you make a request with MaxResults set to 10, and there are 20 matches in the database. The service will return a pagination token as a part of the response. This token can be used to call the API again and get results starting from the 11th match.

    :rtype: dict
    :return: {
        'IdentityId': 'string',
        'DeveloperUserIdentifierList': [
            'string',
        ],
        'NextToken': 'string'
    }
    
    
    :returns: 
    (string) --
    
    """
    pass
