code: def has_shell_command(self, command):
          
          try:
              output = self.shell(['command', '-v',
                                   command]).decode('utf-8').strip()
              return command in output
          except AdbError:
              # If the command doesn't exist, then 'command -v' can return
              # an exit code > 1.
              return False
docs: Checks to see if a given check command exists on the device.
  
          Args:
              command: A string that is the name of the command to check.
  
          Returns:
              A boolean that is True if the command exists and False otherwise.