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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 run_aconvasp_command(command, structure):
 """ Helper function for calling aconvasp with different arguments """

    poscar = Poscar(structure)
    p = subprocess.Popen(command, stdout=subprocess.PIPE,
                         stdin=subprocess.PIPE,
                         stderr=subprocess.PIPE)
    output = p.communicate(input=poscar.get_string())
    return output