True if token is at column.

def _token_at_col_in_line(line, column, token, token_len=None):
    """True if token is at column."""
    if not token_len:
        token_len = len(token)

    remaining_len = len(line) - column

    return (remaining_len >= token_len and
            line[column:column + token_len] == token)