import re
def wof(string, my_word):
	sep=re.compile("[,. ]+")
	words = re.split(sep, string)
	word=list(my_word)
	match=[]
	for w in words:
		st=list(w)
		if len(st)==len(word)-1 and all([letter in word for letter in st]): 
			for i in range(len(word)):
   				test=st[:]
 				test.insert(i, word[i])
 				if test==word:
 					match.append(w)
		elif len(st)==len(word) and all([st.count(letter)==word.count(letter) for letter in st]): 
			count=0
			for i in range(len(st)-1):	
 				test=word[:]	
 				test[i],test[i+1]=test[i+1],test[i]
 				if test==st and test[i]!=test[i+1]:
 					count+=1
 			if count==1:
 				match.append(w)
					
		elif len(st)==len(word):
			pairs=zip(word,st)
			err=0
			for w1,w2 in pairs:
 				if w1!=w2:
					err+=1
			if err==1:
				match.append(w)
		else:
			pass
	return set(match)
print wof("nato, the doggie nataa nt anat says Wof, nate ghytr naat nta bgfd eata nyta nala wof-wof, nat ata.", "nata")

nata@mycomp ~ $ ./wof.py
['nato', 'nate', 'naat', 'nta', 'eata', 'nyta', 'nala', 'nat', 'ata']

[guest@localhost werr]$ python3 -mdoctest werr.test 
**********************************************************************
File "werr.test", line 14, in werr.test
Failed example:
    f('xx', 'xx')
Expected:
    []
Got:
    ['xx']
**********************************************************************
File "werr.test", line 51, in werr.test
Failed example:
    f('wood', 'word')
Expected:
    ['wood']
Got:
    []
**********************************************************************
1 items had failures:
   2 of  30 in werr.test
***Test Failed*** 2 failures.
[guest@localhost werr]$