class_docstr: Chain two or more waiting strategies.
  
  If all strategies are exhausted, the very last strategy is used
  thereafter.
  
  For example::
  
      @retry(wait=wait_chain(*[wait_fixed(1) for i in range(3)] +
                             [wait_fixed(2) for j in range(5)] +
                             [wait_fixed(5) for k in range(4)))
      def wait_chained():
          print("Wait 1s for 3 attempts, 2s for 5 attempts and 5s
                 thereafter.")
code: def __init__(self, *strategies):
      self.strategies = strategies
  
imports: import abc
  import random
  import six
  from tenacity import _utils
label_desc: Use image node_id 1 to create a new wait_chain object from inherited base classes: wait_base with example: obj = wait_chain()