text: Title: Decay Function Showing Incorrect Results Where Length Greater Than 1
  Body: **Which version are you running? The lastest version is on Github. Pip is for major releases.**
  3.99b0
  
  **Do you have _TA Lib_ also installed in your environment?**
  Yes
  
  **Have you tried the _development_ version? Did it resolve the issue?**
  Tested in development version.  
  
  **Describe the bug**
  According to the documentation provided at https://tulipindicators.org/decay if length is 4 and signals are:
  
  [0, 0, 0, 1, 0, 0, 0, 1]
  
  the output of the decay indicator should be:
  
  [0, 0, 0, 1, .75, 0.5, 0.25, 1]
  
  instead the output is:
  
  [0, 0, 0, 1, .75, 0, 0, 1]
  
  **Expected behavior**
  Decay should work for lengths greater than 1 as described in documentation.
  
  
  Thanks for using Pandas TA!
  