code: def verify_branch(branch_name):
      # type: (str) -> bool
      
      try:
          shell.run(
              'git rev-parse --verify {}'.format(branch_name),
              never_pretend=True
          )
          return True
      except IOError:
          return False
docs: Verify if the given branch exists.
  
      Args:
          branch_name (str):
              The name of the branch to check.
  
      Returns:
          bool: **True** if a branch with name *branch_name* exits, **False**
          otherwise.