the user may have
    configured these files differently.

    Examples
    --------
    >>> map = PsfontsMap(find_tex_file('pdftex.map'))
    >>> entry = map[b'ptmbo8r']
    >>> entry.texname
    b'ptmbo8r'
    >>> entry.psname
    b'Times-Bold'
    >>> entry.encoding
    '/usr/local/texlive/2008/texmf-dist/fonts/enc/dvips/base/8r.enc'
    >>> entry.effects
    {'slant': 0.16700000000000001}
    >>> entry.filename
    )