diff --git a/lib/source.tcl b/lib/source.tcl
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+# This file is an aid in sourcing other tcl files.  It provides the following
+# advantages:
+# - It shortens the number of lines of code needed to intelligently source
+# files.
+# - Its my_source procedure provides several benefits (see my_source prolog
+# below).
+
+# By convention, this file, or a link to this file, must exist in one of the
+# directories named in the PATH environment variable.
+
+# Example use:
+# source [exec bash -c "which source.tcl"]
+# my_source [list print.tcl opt.tcl]
+
+set path_list [split $::env(PATH) :]
+
+
+proc tcl_which { file_name } {
+
+  # Search the PATH environment variable for the first executable instance of
+  # $file_name and return the full path.  On failure, return a blank string.
+
+  # This procedure runs much faster than [exec bash -c "which $file_name"].
+
+  # Description of argument(s):
+  # file_name                       The name of the file to be found.
+
+  global path_list
+
+  foreach path $path_list {
+    set file_path $path/$file_name
+    if { [file executable $file_path] } { return $file_path }
+  }
+
+  return ""
+
+}
+
+
+if { ![info exists sourced_files] } {
+  set sourced_files [list]
+}
+
+proc my_source { source_files } {
+
+  # Source each file in the source_files list.
+
+  # This procedure provides the following benefits verses just using the
+  # source command directly.
+  # - Use of PATH environment variable to locate files.
+  # - Better error handling.
+  # - Will only source each file once.
+  # - If "filex" is not found, this procedure will try to find "filex.tcl".
+
+  # Description of argument(s):
+  # source_files                    A list of file names to be sourced.
+
+  global sourced_files
+  global env
+
+  foreach file_name $source_files {
+
+    set file_path [tcl_which $file_name]
+    if { $file_path == "" } {
+      # Does the user specify a ".tcl" extension for this file?
+      set tcl_ext [regexp -expanded {\.tcl$} $file_name]
+      if { $tcl_ext } {
+        append message "**ERROR** Programmer error - Failed to find"
+        append message " \"${file_name}\" source file:\n"
+        append message $::env(PATH)
+        puts stderr $message
+        exit 1
+      }
+
+      set file_path [tcl_which ${file_name}.tcl]
+      if { $file_path == "" } {
+        append message "**ERROR** Programmer error - Failed to find either"
+        append message " \"${file_name}\" or \"${file_name}.tcl\" source file:"
+        append message $::env(PATH)
+        puts stderr $message
+        exit 1
+      }
+    }
+
+    # Adjust name (in case we found the .tcl version of a file).
+    set full_file_name "[file tail $file_path]"
+
+    # Have we already attempted to source this file?
+    if { [lsearch -exact $sourced_files $full_file_name] != -1 } { continue }
+    # Add the file name to the list of sourced files.  It is important to add
+    # this file to the list BEFORE we source the file.  Otherwise, if there is
+    # a recursive source (a sources b, b sources c, c sources a), we will get
+    # into an infinite loop.
+    lappend sourced_files $full_file_name
+
+    if { [catch { uplevel 1 source $file_path } result] } {
+      append message "**ERROR** Programmer error - Failed to source"
+      append message " \"${file_path}\":\n${result}"
+      puts stderr $message
+
+      exit 1
+    }
+  }
+
+}