
  -spec list_to_integer(String) -> integer() when String :: string().

  Returns an integer whose text representation is String, for
  example:

    > list_to_integer("123").
    123

    > list_to_integer("-123").
    -123

    > list_to_integer("+123234982304982309482093833234234").
    123234982304982309482093833234234

  String must contain at least one digit character and can have an
  optional prefix consisting of a single "+" or "-" character
  (that is, String must match the regular expression 
  "^[+-]?[0-9]+$").

  Failure: badarg if String contains a bad representation of an
  integer.
