[Tutor] Why do I not get an error when I mistakenly type "humdrum.sigh_strenght" instead of the correct "humdrum.sigh_strength"?

[boB Stepp]

My intent was to deliberately introduce an error into my class definition:

>>> class Hmm(object):
        def __init__(self, sigh_type, sigh_strength):
            self.sigh_type = sigh_type
            self.sigh_strength = sigh_strength
        def snort(self):
            if self.sigh_strength == 'low':
                print("snort")
            elif self.sigh_strength == 'med':
                print("Snort!")
            elif self.sigh_strenght == 'high':
                print("SNORT!!!")
            else:
                print("Hmm...")
        def sigh():
            if self.sigh_type == 'quiet':
                print("pssssss")
            elif self.sigh_type == 'annoying':
                print("Whoosh!")
            elif self.sigh_type == 'loud':
                print("HEAVY SIGH!!!")
            else:
                print("HMM!!!")

I omitted "self" from the sigh() method to see what would happen plus
some other things.

>>> humdrum = Hmm('quiet', 'low')
>>> humdrum.snort()
snort
>>> humdrum.sigh_strength = 'med'
>>> humdrum.snort()
Snort!
>>> humdrum.sigh_strenght = 'high'
>>> humdrum.snort()
Snort!

At this point I wondered why my output was not "SNORT!!!".  Then I
noticed my typo.  But now I wonder why I did not get an error from
this typo?

>>> humdrum.sigh_strength = 'high'
>>> humdrum.snort()
SNORT!!!
>>> humdrum.sigh()
Traceback (most recent call last):
  File "<pyshell#232>", line 1, in <module>
    humdrum.sigh()
TypeError: sigh() takes 0 positional arguments but 1 was given

This was my original point in doing all of this, to see what would
result if I omitted "self".  I am pretty sure the error is because the
object instance gets automatically passed to the sigh() method, but by
leaving the "self" parameter out in the method definition, I have a
mismatch between what was defined (0 parameters) and what was passed
to the method (1 argument).

>>> humdrum.sigh_strenght
'high'

But what about this?  It seems like I can use the humdrum arguments
outside of the Hmm class and merrily define new variables.  Why is
this?  Is this potentially useful behavior?

-- 
boB