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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 get_structure_from_mp(formula):
 """ Convenience method to get a crystal from the Materials Project database via the API. Requires PMG_MAPI_KEY to be set. Args: formula (str):
 A formula Returns: (Structure) The lowest energy structure in Materials Project with that formula. """

    m = MPRester()
    entries = m.get_entries(formula, inc_structure="final")
    if len(entries) == 0:
        raise ValueError("No structure with formula %s in Materials Project!" %
                         formula)
    elif len(entries) > 1:
        warnings.warn("%d structures with formula %s found in Materials "
                      "Project. The lowest energy structure will be returned." %
                      (len(entries), formula))
    return min(entries, key=lambda e: e.energy_per_atom).structure