String processing

You can change (substitute) characters in a string by using the method replace. For example, suppose we wish to replace all occurrences of '$' in the string price with '£':

price =  'eggs $2, cheese $4'

price = price.replace('$', '£')      # Replace $ by £ in the string price

If we print price, we now get 'eggs £2, cheese £4'.

Other string methods are upper() (convert text to upper case), lstrip() (remove leading characters), and rstrip() (remove trailing characters). Let x ='###this Is A test???'. Consider the following sequence:

x = x.lstrip('#')      # Remove left-hand leading '#' characters to get x = 'this Is A test???'
x = x.rstrip('?')      # Remove right-hand trailing '?' characters to get x = 'this...