def METHOD_NAME(fname, initial=None):
    """Reads requires.txt file generated by setuptools and outputs a
    new/updated dict of extras as keys and corresponding lists of dependencies
    as values.
    The input file's contents are similar to a `ConfigParser` file, e.g.
    pkg_1
    pkg_2
    pkg_3
    [extras1]
    pkg_4
    pkg_5
    [extras2]
    pkg_6
    pkg_7
    """
    reqs = {} if initial is None else initial
    cline = None
    with open(fname, "r") as f:
        for line in f.readlines():
            line = line[:-1].strip()
            if len(line) == 0:
                continue
            if line[0] == "[":
                # Add new key for current extras (if missing in dict)
                cline = line[1:-1].strip()
                if cline not in reqs:
                    reqs[cline] = []
            else:
                # Only keep dependencies from extras
                if cline is not None:
                    reqs[cline].append(line)
    return reqs