type string 
A line is simply a string, possibly empty, that does not contain a
    newline character. As the name suggests, usually such strings are
    obtained by reading a file line by line.
 
val string_to_lines : string -> t list * bool
string_to_lines s splits s on newline characters, returning
    the resuling list of lines. The returned bool is true if the final
    line ended with a newline, or false otherwise.
 
val of_string_unsafe : string -> t
Return the given string without checking that it is a line. Useful
    for efficiency reasons if you're certain the given string is a
    line.
 
Standard String Operations
val lstrip : ?drop:(char -> bool) -> t -> t
 
val rstrip : ?drop:(char -> bool) -> t -> t
 
val strip : ?drop:(char -> bool) -> t -> t
 
val split : t -> on:char -> string list
 
val for_all : string -> f:(char -> bool) -> bool
 
S-Expressions