'Consumes the length portion of C{self._remainingData}.
@raise IncompleteNetstring: if C{self._remainingData} contains
a partial length specification (digits without trailing
comma).
@raise NetstringParseError: if the received data do not form a valid
netstring.'

def _consumeLength(self):

    lengthMatch = self._LENGTH.match(self._remainingData)
    if (not lengthMatch):
        self._checkPartialLengthSpecification()
        raise IncompleteNetstring()
    self._processLength(lengthMatch)
