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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def find_pip(pip_version=None, python_version=None):
 """Find a pip exe using the given python version. Returns: 2-tuple: str: pip executable; `ResolvedContext`: Context containing pip, or None if we fell back to system pip. """

    pip_exe = "pip"

    try:
        context = create_context(pip_version, python_version)
    except BuildError as e:
        # fall back on system pip. Not ideal but at least it's something
        from rez.backport.shutilwhich import which

        pip_exe = which("pip")

        if pip_exe:
            print_warning(
                "pip rez package could not be found; system 'pip' command (%s) "
                "will be used instead." % pip_exe)
            context = None
        else:
            raise e

    return pip_exe, context