13.15 The string type

append($x$)
The append($x$) method appends the string $x$ to the end of a string.

beginsWith($x$)
The beginsWith($x$) method returns a boolean indicating whether a string begins with the substring $x$.

endsWith($x$)
The endsWith($x$) method returns a boolean indicating whether a string ends with the substring $x$.

find($x$)
The find($x$) method returns the position of the first occurrence of $x$ in a string, or $-1$ if it is not found.

findAll($x$)
The findAll($x$) method returns a list of the positions where the substring $x$ occurs in a string.

isalnum()
The isalnum() method returns a boolean indicating whether all of the characters of a string are alphanumeric.

isalpha()
The isalpha() method returns a boolean indicating whether all of the characters of a string are alphabetic.

isdigit()
The isdigit() method returns a boolean indicating whether all of the characters of a string are numeric.

len()
The len() method returns the length of a string.

lower()
The lower() method converts a string to lowercase.

lstrip()
The lstrip() method strips whitespace off the beginning of a string.

split()
The split() method returns a list of all the whitespace-separated words in a string.

splitOn(...)
The splitOn(...) method splits a string whenever it encounters any of the substrings supplied as arguments, and returns a list of the split string segments.

strip()
The strip() method strips whitespace off the beginning and end of a string.

rstrip()
The rstrip() method strips whitespace off the end of a string.

upper()
The upper() method converts a string to uppercase.