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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 load(filepath=None):
 """ Reads a .env file into os.environ. For a set filepath, open the file and read contents into os.environ. If filepath is not set then look in current dir for a .env file. """

    if filepath and os.path.exists(filepath):
        pass
    else:
        if not os.path.exists('.env'):
            return False
        filepath = os.path.join('.env')

    for key, value in _get_line_(filepath):
        # set the key, value in the python environment vars dictionary
        # does not make modifications system wide.
        os.environ.setdefault(key, str(value))
    return True