def atom(ch:str):
  """atom(ch) - ascii-to-multiplier - converts ascii char to a time miltiplier.
    eg: s=seconds, m=minutes, h=hours, d=days, w=weeks, c=calendar=months, y=years"""
  
  ch=ch.lower()
  if ch == 's':
    mult = 1
  elif ch =='m':
    mult = 60
  elif ch == 'h':
    mult = 60*60
  elif ch == 'd':
    mult = 60*60*24
  elif ch == 'w':
    mult = 60*60*24*7
  elif ch == 'c':
    mult = 60*60*24*30
  elif ch == 'y':
    mult = 60*60*24*365
  else:
    mult = None
    
  return mult