"""Backport of importlib.import_module from 3.x.

Downloaded from: https://github.com/sprintly/importlib

This code is based in the implementation of importlib.import_module()
in Python 2.7. The license is below.

========================================================================

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"""

# While not critical (and in no way guaranteed!), it would be nice to keep this
# code compatible with Python 2.3.
import sys
import six


def _resolve_name(name, package, level):
    """Return the absolute name of the module to be imported."""
    if not hasattr(package, 'rindex'):
        raise ValueError("'package' not set to a string")
    dot = len(package)
    for _ in six.moves.xrange(level, 1, -1):
        try:
            dot = package.rindex('.', 0, dot)
        except ValueError:
            raise ValueError("attempted relative import beyond top-level "
                             "package")
    return "%s.%s" % (package[:dot], name)


def import_module(name, package=None):
    """Import a module.
    The 'package' argument is required when performing a relative import. It
    specifies the package to use as the anchor point from which to resolve the
    relative import to an absolute import.
    """
    if name.startswith('.'):
        if not package:
            raise TypeError("relative imports require the 'package' argument")
        level = 0
        for character in name:
            if character != '.':
                break
            level += 1
        name = _resolve_name(name[level:], package, level)
    __import__(name)
    return sys.modules[name]