how to run the exception when the try have no error code example

Example 1: catch error python

import traceback

dict = {'a':3,'b':5,'c':8}
try:
  print(dict[q])
 
except:
  traceback.print_exc()
  
# This will trace you back to the line where everything went wrong. 
# So in this case you will get back line 5

Example 2: python: raise error

class MyError(TypeError):
    pass

raise MyError('An error happened')