Capitalize string

Capitalizes the first letter of a string.

• Use list slicing and str.upper() to capitalize the first letter of the string.
• Use str.join() to combine the capitalized first letter with the rest of the characters.
• Omit the lower_rest parameter to keep the rest of the string intact, or set it to True to convert to lowercase.

def capitalize(s, lower_rest = False):
  return ''.join([s[:1].upper(), (s[1:].lower() if lower_rest else s[1:])])

capitalize('fooBar') # 'FooBar'
capitalize('fooBar', True) # 'Foobar'