'Helper function that reads in a feature structure.
:param s: The string to read.
:param position: The position in the string to start parsing.
:param reentrances: A dictionary from reentrance ids to values.
Defaults to an empty dictionary.
:return: A tuple (val, pos) of the feature structure created by
parsing and the position where the parsed feature structure ends.
:rtype: bool'

def read_partial(self, s, position=0, reentrances=None, fstruct=None):

    if (reentrances is None):
        reentrances = {}
    try:
        return self._read_partial(s, position, reentrances, fstruct)
    except ValueError as e:
        if (len(e.args) != 2):
            raise
        self._error(s, *e.args)
