def charsUntil(self, characters, opposite=False):
        """ Returns a string of characters from the stream up to but not
        including any character in 'characters' or EOF. 'characters' must be
        a container that supports the 'in' method and iteration over its
        characters.
        """

        # Use a cache of regexps to find the required characters
        try:
            chars = charsUntilRegEx[(characters, opposite)]
        except KeyError:
            if __debug__:
                for c in characters:
                    assert(ord(c) < 128)
            regex = "".join(["\\x%02x" % ord(c) for c in characters])
            if not opposite:
                regex = "^%s" % regex
            chars = charsUntilRegEx[(characters, opposite)] = re.compile("[%s]+" % regex)

        rv = []

        while True:
            # Find the longest matching prefix
            m = chars.match(self.chunk, self.chunkOffset)
            if m is None:
                # If nothing matched, and it wasn't because we ran out of chunk,
                # then stop
                if self.chunkOffset != self.chunkSize:
                    break
            else:
                end = m.end()
                # If not the whole chunk matched, return everything
                # up to the part that didn't match
                if end != self.chunkSize:
                    rv.append(self.chunk[self.chunkOffset:end])
                    self.chunkOffset = end
                    break
            # If the whole remainder of the chunk matched,
            # use it all and read the next chunk
            rv.append(self.chunk[self.chunkOffset:])
            if not self.readChunk():
                # Reached EOF
                break

        r = "".join(rv)
        return r
 Returns a string of characters from the stream up to but not
        including any character in 'characters' or EOF. 'characters' must be
        a container that supports the 'in' method and iteration over its
        characters.
        
stackoverflow/venv/lib/python3.6/site-packages/pip-19.0.3-py3.6.egg/pip/_vendor/html5lib/_inputstream.py