Make your strings more nerdy: Replace all 'a'/'A' with 4, 'e'/'E' with 3 and 'l' with 1
e.g. "Fundamentals" --> "Fund4m3nt41s"
```if:csharp
Documentation:
Kata.Nerdify Method (String)
Nerdifies a string. Returns a copy of the original string with 'a'/'A' characters replaced with '4', 'e'/'E' characters replaced with '3', and 'l' characters replaced with '1'.
Syntax
public
static
string Nerdify(
string str
    )
Parameters
str
Type: System.String
The string to be nerdified.
Return Value
Type: System.String
  The nerdified string.
Exceptions
Exception
Condition
ArgumentNullException
str is null.
```
def nerdify(txt):
    new_txt = ""
    for letter in txt:
        if letter == "a" or letter == "A":
            new_txt += "4"
        elif letter == "e" or letter == "E":
            new_txt += "3"
        elif letter == "l":
            new_txt += "1"
        else:
            new_txt += letter
    return new_txt
def nerdify(txt):
    new_txt = ""
    for letter in txt:
        if letter == "a" or letter == "A":
            new_txt += "4"
        elif letter == "e" or letter == "E":
            new_txt += "3"
        elif letter == "l":
            new_txt += "1"
        else:
            new_txt += letter
    return new_txt