code: def get_all_context_names(context_num):
      
      if context_num == 0:
          return ['None']
      elif context_num == 1:
          return ['A', 'C', 'T', 'G']
      elif context_num == 1.5:
          return ['C*pG', 'CpG*', 'TpC*', 'G*pA',
                  'A', 'C', 'T', 'G']
      elif context_num == 2:
          dinucs = list(set(
              [d1+d2
               for d1 in 'ACTG'
               for d2 in 'ACTG']
          ))
          return dinucs
      elif context_num == 3:
          trinucs = list(set(
              [t1+t2+t3
               for t1 in 'ACTG'
               for t2 in 'ACTG'
               for t3 in 'ACTG']
          ))
          return trinucs
docs: Based on the nucleotide base context number, return
      a list of strings representing each context.
  
      Parameters
      ----------
      context_num : int
          number representing the amount of nucleotide base context to use.
  
      Returns
      -------
          a list of strings containing the names of the base contexts