code: def rsi(f, c, p=14):
      r"""Calculate the Relative Strength Index (RSI).
  
      Parameters
      ----------
      f : pandas.DataFrame
          Dataframe containing the column ``net``.
      c : str
          Name of the column in the dataframe ``f``.
      p : int
          The period over which to calculate the RSI.
  
      Returns
      -------
      new_column : pandas.Series (float)
          The array containing the new feature.
  
      References
      ----------
      *Developed by J. Welles Wilder, the Relative Strength Index (RSI) is a momentum
      oscillator that measures the speed and change of price movements* [SC_RSI]_.
  
      .. [SC_RSI] http://stockcharts.com/school/doku.php?id=chart_school:technical_indicators:relative_strength_index_rsi
  
      """
      cdiff = "net"
      vexec(f, cdiff)
      f["pval"] = upc(f, cdiff)
      f["mval"] = dpc(f, cdiff)
      upcs = ma(f, "pval", p)
      dpcs = ma(f, "mval", p)
      new_column = 100 - (100 / (1 + (upcs / dpcs)))
      return new_column
  
imports: from alphapy.calendrical import biz_day_month
  from alphapy.calendrical import biz_day_week
  from alphapy.globals import NULLTEXT
  from alphapy.globals import BSEP, PSEP, USEP
  from alphapy.variables import vexec
  import itertools
  import logging
  import math
  import numpy
  import pandas
label_desc: Use image node_id 38 for calling a global function with example usage: rsi(f, c, p) and returns: new_column