# indie:lang_version = 5
from indie import indicator, format, param, level, color, plot, MutSeriesF
from indie.algorithms import Change, Ema


@indicator('EFI', format=format.VOLUME)  # Elders Force Index
@param.int('length', default=13, min=1)
@level(0, line_color=color.GRAY, title='Zero')
@plot.line(color=color.RED, title='Elders Force Index')
def Main(self, length):
    efi = Change.new(self.close)[0] * self.volume[0]
    return Ema.new(MutSeriesF.new(efi), length)[0]