Remove is_sourced functionality, it's not needed anymore

ghcup

@@ -1003,34 +1003,6 @@ posix_realpath() {
     unset mysource mydir posix_realpath_error
 }
 
-# @FUNCTION: is_sourced
-# @DESCRIPTION:
-# Tries to figure out if we are being sourced. Based on
-#   https://stackoverflow.com/a/28776166
-# @RETURNS: 0 if we are being sourced, 1 otherwise
-is_sourced() {
-    if [ -n "$ZSH_EVAL_CONTEXT" ]; then
-        case $ZSH_EVAL_CONTEXT in
-           *:file)
-               return 0 ;;
-       esac
-    elif [ -n "$KSH_VERSION" ]; then
-        # shellcheck disable=SC2154
-        [ "$(cd "$(dirname -- "$0")" && pwd -P)/$(basename -- "$0")" != "$(cd "$(dirname -- "${.sh.file}")" && pwd -P)/$(basename -- "${.sh.file}")" ] && return 0
-    elif [ -n "$BASH_VERSION" ]; then
-        # shellcheck disable=SC2128
-        [ "$0" != "$BASH_SOURCE" ] && return 0
-    else # All other shells: examine $0 for known shell binary filenames
-        # Detects `sh` and `dash`; add additional shell filenames as needed.
-        case ${0##*/} in
-            sh|dash)
-               return 0 ;;
-       esac
-   fi
-
-   # assume we are not sourced, if our above checks didn't find it
-   return 1
-}
 
 # @FUNCTION: get_meta_version_file
 # @DESCRIPTION:
@@ -1689,8 +1661,6 @@ fi
     #--[ Command line parsing and entry point ]--#
     ##############################################
 
-if ! is_sourced ; then
-
 [ $# -lt 1 ] && usage
 
 while [ $# -gt 0 ] ; do
@@ -1920,6 +1890,5 @@ if ! is_sourced ; then
        break;;
     esac
 done
-fi # is_sourced
 
 # vim: tabstop=4 shiftwidth=4 expandtab