'Constructs a synapse error.
Args:
code (int): The integer error code (an HTTP response code)
msg (str): The human-readable error message.
errcode (str): The matrix error code e.g \'M_FORBIDDEN\''

def __init__(self, code, msg, errcode=Codes.UNKNOWN):

    super(SynapseError, self).__init__(code, msg)
    self.errcode = errcode
