How to use the pysces.lib.lex.LexToken function in pysces

lexpos    = self.lexpos         # This is here in case user has updated lexpos.
                    lexignore = self.lexignore      # This is here in case there was a state change
                    break

                # Verify type of the token.  If not in the token map, raise an error
                if not self.lexoptimize:
                    if newtok.type not in self.lextokens_all:
                        raise LexError("%s:%d: Rule '%s' returned an unknown token type '%s'" % (
                            func.__code__.co_filename, func.__code__.co_firstlineno,
                            func.__name__, newtok.type), lexdata[lexpos:])

                return newtok
            else:
                # No match, see if in literals
                if lexdata[lexpos] in self.lexliterals:
                    tok = LexToken()
                    tok.value = lexdata[lexpos]
                    tok.lineno = self.lineno
                    tok.type = tok.value
                    tok.lexpos = lexpos
                    self.lexpos = lexpos + 1
                    return tok

                # No match. Call t_error() if defined.
                if self.lexerrorf:
                    tok = LexToken()
                    tok.value = self.lexdata[lexpos:]
                    tok.lineno = self.lineno
                    tok.type = 'error'
                    tok.lexer = self
                    tok.lexpos = lexpos
                    self.lexpos = lexpos

return newtok
            else:
                # No match, see if in literals
                if lexdata[lexpos] in self.lexliterals:
                    tok = LexToken()
                    tok.value = lexdata[lexpos]
                    tok.lineno = self.lineno
                    tok.type = tok.value
                    tok.lexpos = lexpos
                    self.lexpos = lexpos + 1
                    return tok

                # No match. Call t_error() if defined.
                if self.lexerrorf:
                    tok = LexToken()
                    tok.value = self.lexdata[lexpos:]
                    tok.lineno = self.lineno
                    tok.type = 'error'
                    tok.lexer = self
                    tok.lexpos = lexpos
                    self.lexpos = lexpos
                    newtok = self.lexerrorf(tok)
                    if lexpos == self.lexpos:
                        # Error method didn't change text position at all. This is an error.
                        raise LexError("Scanning error. Illegal character '%s'" % (lexdata[lexpos]), lexdata[lexpos:])
                    lexpos = self.lexpos
                    if not newtok:
                        continue
                    return newtok

                self.lexpos = lexpos

lexdata   = self.lexdata

        while lexpos < lexlen:
            # This code provides some short-circuit code for whitespace, tabs, and other ignored characters
            if lexdata[lexpos] in lexignore:
                lexpos += 1
                continue

            # Look for a regular expression match
            for lexre, lexindexfunc in self.lexre:
                m = lexre.match(lexdata, lexpos)
                if not m:
                    continue

                # Create a token for return
                tok = LexToken()
                tok.value = m.group()
                tok.lineno = self.lineno
                tok.lexpos = lexpos

                i = m.lastindex
                func, tok.type = lexindexfunc[i]

                if not func:
                    # If no token type was set, it's an ignored token
                    if tok.type:
                        self.lexpos = m.end()
                        return tok
                    else:
                        lexpos = m.end()
                        break

tok.lexpos = lexpos
                    self.lexpos = lexpos
                    newtok = self.lexerrorf(tok)
                    if lexpos == self.lexpos:
                        # Error method didn't change text position at all. This is an error.
                        raise LexError("Scanning error. Illegal character '%s'" % (lexdata[lexpos]), lexdata[lexpos:])
                    lexpos = self.lexpos
                    if not newtok:
                        continue
                    return newtok

                self.lexpos = lexpos
                raise LexError("Illegal character '%s' at index %d" % (lexdata[lexpos], lexpos), lexdata[lexpos:])

        if self.lexeoff:
            tok = LexToken()
            tok.type = 'eof'
            tok.value = ''
            tok.lineno = self.lineno
            tok.lexpos = lexpos
            tok.lexer = self
            self.lexpos = lexpos
            newtok = self.lexeoff(tok)
            return newtok

        self.lexpos = lexpos + 1
        if self.lexdata is None:
            raise RuntimeError('No input string given with input()')
        return None