code: def plotting_pos(nobs, a=0.0, b=None):
      """
      Generates sequence of plotting positions
  
      Parameters
      ----------
      nobs : int
          Number of probability points to plot
      a : float, default 0.0
          alpha parameter for the plotting position of an expected order
          statistic
      b : float, default None
          beta parameter for the plotting position of an expected order
          statistic. If None, then b is set to a.
  
      Returns
      -------
      ndarray
          The plotting positions
  
      Notes
      -----
      The plotting positions are given by (i - a)/(nobs + 1 - a - b) for i in
      range(1, nobs+1)
  
      See Also
      --------
      scipy.stats.mstats.plotting_positions
          Additional information on alpha and beta
      """
      b = a if b is None else b
      return (np.arange(1.0, nobs + 1) - a) / (nobs + 1 - a - b)
  
imports: from statsmodels.compat.python import lzip
  import numpy
  from scipy import stats
  from statsmodels.distributions import ECDF
  from statsmodels.regression.linear_model import OLS
  from statsmodels.tools.decorators import cache_readonly
  from statsmodels.tools.tools import add_constant
  from .None import utils
label_desc: Use image node_id 4 for calling a global function with example usage: plotting_pos(nobs, a, b) and returns: unknown