def parse_keywords(strings=[]):
    """Parse keywords specifications from the given list of strings.

    >>> kw = sorted(parse_keywords(['_', 'dgettext:2', 'dngettext:2,3', 'pgettext:1c,2']).items())
    >>> for keyword, indices in kw:
    ...     print((keyword, indices))
    ('_', None)
    ('dgettext', (2,))
    ('dngettext', (2, 3))
    ('pgettext', ((1, 'c'), 2))
    """
    keywords = {}
    for string in strings:
        if ':' in string:
            funcname, indices = string.split(':')
        else:
            funcname, indices = string, None
        if funcname not in keywords:
            if indices:
                inds = []
                for x in indices.split(','):
                    if x[-1] == 'c':
                        inds.append((int(x[:-1]), 'c'))
                    else:
                        inds.append(int(x))
                indices = tuple(inds)
            keywords[funcname] = indices
    return keywords