<human>:  What is a good Python function to determine existence? What is python function? Python functions determine existence.
<bot>: Here is a Python function to determine existence

import os

def is_pid_set(pid):
  """Determines if a pid is set.

  If pid is not set, returns False.
  If pid is set, returns True.
  """
  return pid is not None

# Enter the pid
pid = 12345

# Calling the function
print((is_pid_set(pid)))

#Example Output
# True

#Remember to inspect code for bugs.