how to fix TypeError: ‘str’ object is not callable in Python

Im gettng this error:

f.write("n"(var13))

SyntaxWarning: ‘str’ object is not callable; perhaps you missed a comma?

For code:

if (var11 == "register/"):
     usernamer=input("Username : ")
     var12 = usernamer
     f= open("Username.txt","a+")
     for i in range(1):
             f.write("n"(var12))
     f.close()

Answer

The concatenation of strings works differently.

f.write(f"{var12}n")

if you use Python 3.6+ or

f.write(var12 + "n")

for earlier versions.

You can also do as follows:

if (var11 == "register/"):
     username = input("Username : ")
     with open("Username.txt","a+") as f:
          f.write(f"{usernamer}n")

which makes your code more concise and pythonic.