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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_input(cls, input, workdir=None, manager=None):
 """ Create an instance of `AbinitTask` from an ABINIT input. Args: ainput: `AbinitInput` object. workdir: Path to the working directory. manager: :class:`TaskManager` object. """

        return cls(input, workdir=workdir, manager=manager)