def METHOD_NAME(libname, flag, encoding=sys.getfilesystemencoding()):
    """Calls pkg-config and returns the output if found
    """
    a = ["pkg-config", "--print-errors"]
    a.append(flag)
    a.append(libname)
    try:
        pc = subprocess.Popen(a, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    except EnvironmentError as e:
        raise PkgConfigError("cannot run pkg-config: %s" % (str(e).strip(),))
    bout, berr = pc.communicate()
    if pc.returncode != 0:
        try:
            berr = berr.decode(encoding)
        except Exception:
            pass
        raise PkgConfigError(berr.strip())
    if sys.version_info >= (3,) and not isinstance(bout, str):   # Python 3.x
        try:
            bout = bout.decode(encoding)
        except UnicodeDecodeError:
            raise PkgConfigError("pkg-config %s %s returned bytes that cannot "
                                 "be decoded with encoding %r:\n%r" %
                                 (flag, libname, encoding, bout))
    if os.altsep != '\\' and '\\' in bout:
        raise PkgConfigError("pkg-config %s %s returned an unsupported "
                             "backslash-escaped output:\n%r" %
                             (flag, libname, bout))
    return bout