In addition to the standard line comments defined by R5RS, Guile has
another comment type for multiline comments, called block
comments. This type of comment begins with the character sequence
#! and ends with the characters !#, which must appear on a
line of their own. These comments are compatible with the block
comments in the Scheme Shell scsh (see The Scheme shell (scsh)). The characters #! were chosen because they are the
magic characters used in shell scripts for indicating that the name of
the program for executing the script follows on the same line.
Thus a Guile script often starts like this.
#! /usr/local/bin/guile -s
!#
More details on Guile scripting can be found in the scripting section (see Guile Scripting).