backwards compatibility for python 2/3 dictionary calls

Python_2_3_dict_compat.py

def iterkeys(d):
    """Python 2/3 compatibility function for dict.iterkeys()"""
    if __python_version_major >= 3:
        return d.keys()
    else:
        return d.iterkeys()


def itervalues(d):
    """Python 2/3 compatibility function for dict.itervalues()"""
    if __python_version_major >= 3:
        return d.values()
    else:
        return d.itervalues()


def iteritems(d):
    """Python 2/3 compatibility function for dict.iteritems()"""
    if __python_version_major >= 3:
        return d.items()
    else:
        return d.iteritems()