code: def _get_alpha(i, n, start=0.4, end=1.0):
      """Compute alpha value at position i out of n"""
      return start + (1 + i) * (end - start) / n
  
file_path: joypy/joypy/joyplot.py
imports: import numpy
  from scipy.stats import gaussian_kde
  import scipy.stats
  import warnings
  from pandas import DataFrame, Series
  from pandas.core.dtypes.common import is_number
  from pandas.core.groupby import DataFrameGroupBy
  from matplotlib import pyplot
  from warnings import warn
label_desc: Use image node_id 4 for calling a global function with example usage: _get_alpha(i, n, start, end) and returns: unknown