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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 field(self, name, from_study=None):
 """ Gets the field named 'name' produced by the Study named 'study' if provided. If a spec is passed instead of a str to the name argument, then the study will be set from the spec iff it is derived Parameters name : str | BaseField The name of the field or a spec matching the given name study : str | None Name of the study that produced the field if derived. If None and a spec is passed instaed of string to the name argument then the study name will be taken from the spec instead. """

        if isinstance(name, BaseField):
            if from_study is None and name.derived:
                from_study = name.study.name
            name = name.name
        try:
            return self._fields[(name, from_study)]
        except KeyError:
            available = [d.name for d in self.fields
                         if d.from_study == from_study]
            other_studies = [(d.from_study if d.from_study is not None
                              else '<root>')
                             for d in self.fields
                             if d.name == name]
            if other_studies:
                msg = (". NB: matching field(s) found for '{}' study(ies) "
                       "('{}')".format(name, "', '".join(other_studies)))
            else:
                msg = ''
            raise ArcanaNameError(
                name, ("{} doesn't have a field named '{}'{} "
                       "(available '{}')"
                       .format(
                           self, name,
                           (" from study '{}'".format(from_study)
                            if from_study is not None else ''),
                           "', '".join(available), msg)))