@sh.add_function(dsp, outputs=['first_gear_box_ratio'])
def identify_first_gear_box_ratio(gear_box_ratios):
"""
Identify the gear box ratio of first gear.
:param gear_box_ratios:
Gear box ratios [-].
:type gear_box_ratios: dict[int, float | int]
:return:
Gear box ratio of first gear [-].
:return: float
"""
return gear_box_ratios.get(1, sh.NONE)