Replace'a character'with'specified character'

Replace'learning' in "I'm learning Python" with'******'. ( of the number of characters you want to replace)

def censor(text,word):
    x = []
    star = "*"*len(word)
    for i in text.split():
        x.append(i)
    for j in x:
        if j == word:
            x.insert(x.index(word),star)
            x.remove(j)
    return " ".join(x)
    
print censor("I'm learning Python", "learning")

Another pattern.

def censor(text, word):
    x = text.split()
    for i in x:
        if i == word:
            x[x.index(i)]= "*"*len(word) 
    return " ".join(x)
print censor("I'm learning Python", "learning")

However, it is better to use enumerate () because it takes a long time to process the above.

def censor(text,word):
    x = []
    star = "*"*len(word)
    for i in text.split():
        x.append(i)
    for index,j in enumerate(x):#here
        if j == word:
            x.insert(index,star)#here
            x.remove(j)
    return " ".join(x)
    
print censor("I'm learning Python", "learning")

def censor(text, word):
    x = text.split()
    for index,i in enumerate(x):#here
        if i == word:
            x[index]= "*"*len(word)#here
    return " ".join(x)
print censor("I'm learning Python", "learning")

Thank you @usai!