The task can be solved using the following piece of code, [0:28] being interval where the name is being held, while [29:34] contains the actual pid.
import os
program_pid = 0
program_name = "notepad.exe"
task_manager_lines = os.popen("tasklist").readlines()
for line in task_manager_lines:
try:
if str(line[0:28]) == program_name + (28 - len(program_name) * ' ': #so it includes the whitespaces
program_pid = int(line[29:34])
break
except:
pass
print(program_pid)