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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 from_config(cls, config, prefix="postmark_", is_uppercase=False):
 """ Helper method for instantiating PostmarkClient from dict-like objects. """

        kwargs = {}
        for arg in get_args(cls):
            key = prefix + arg
            if is_uppercase:
                key = key.upper()
            else:
                key = key.lower()
            if key in config:
                kwargs[arg] = config[key]
        return cls(**kwargs)