Python: Is there an equivalent of mid, right, and left from BASIC?

Question

I want to do something like this:

    >>> mystring = \"foo\"
    >>> print(mid(mystring))

Help!

Answer 1

These work great for reading left / right "n" characters from a string, but, at least with BBC BASIC, the LEFT$() and RIGHT$() functions allowed you to change the left / right "n" characters too...

E.g.:

10 a$="00000"
20 RIGHT$(a$,3)="ABC"
30 PRINT a$

Would produce:

00ABC

Edit : Since writing this, I've come up with my own solution...

def left(s, amount = 1, substring = ""):
    if (substring == ""):
        return s[:amount]
    else:
        if (len(substring) > amount):
            substring = substring[:amount]
        return substring + s[:-amount]

def right(s, amount = 1, substring = ""):
    if (substring == ""):
        return s[-amount:]
    else:
        if (len(substring) > amount):
            substring = substring[:amount]
        return s[:-amount] + substring

To return n characters you'd call

substring = left(string,<n>)

Where defaults to 1 if not supplied. The same is true for right()

To change the left or right n characters of a string you'd call

newstring = left(string,<n>,substring)

This would take the first n characters of substring and overwrite the first n characters of string, returning the result in newstring. The same works for right().