gulp-imagemin error 'parseSignature: expected comma after expression'

[LayneSmith]

When I place an image into images and run gulp I get the following error...

[07:38:10] Using gulpfile ~/Desktop/gitHub/interactive_dirk-museum/gulpfile.js
[07:38:10] Starting 'assets'...
[07:38:10] Starting 'img'...
[07:38:10] Starting 'optimize-images'...
[07:38:10] Starting 'scss'...
[07:38:10] Starting 'watchify'...
[07:38:10] Starting 'templates'...
[07:38:10] Starting 'server'...
[07:38:10] Finished 'server' after 17 ms
[07:38:10] gulp-imagemin: Minified 0 images

events.js:183
      throw er; // Unhandled 'error' event
      ^
Template render error: (unknown path) [Line 122, Column 40]
  parseSignature: expected comma after expression
    at Object.exports.prettifyError (/Users/lsmith/Desktop/gitHub/interactive_dirk-museum/node_modules/nunjucks/src/lib.js:34:15)
    at new_cls.render (/Users/lsmith/Desktop/gitHub/interactive_dirk-museum/node_modules/nunjucks/src/environment.js:469:27)
    at new_cls.renderString (/Users/lsmith/Desktop/gitHub/interactive_dirk-museum/node_modules/nunjucks/src/environment.js:327:21)
    at Object.module.exports.renderString (/Users/lsmith/Desktop/gitHub/interactive_dirk-museum/node_modules/nunjucks/index.js:80:14)
    at Transform._transform (/Users/lsmith/Desktop/gitHub/interactive_dirk-museum/node_modules/gulp-nunjucks-render/index.js:49:21)
    at Transform._read (/Users/lsmith/Desktop/gitHub/interactive_dirk-museum/node_modules/gulp-nunjucks-render/node_modules/readable-stream/lib/_stream_transform.js:184:10)
    at Transform._write (/Users/lsmith/Desktop/gitHub/interactive_dirk-museum/node_modules/gulp-nunjucks-render/node_modules/readable-stream/lib/_stream_transform.js:172:12)
    at doWrite (/Users/lsmith/Desktop/gitHub/interactive_dirk-museum/node_modules/gulp-nunjucks-render/node_modules/readable-stream/lib/_stream_writable.js:237:10)
    at writeOrBuffer (/Users/lsmith/Desktop/gitHub/interactive_dirk-museum/node_modules/gulp-nunjucks-render/node_modules/readable-stream/lib/_stream_writable.js:227:5)
    at Transform.Writable.write (/Users/lsmith/Desktop/gitHub/interactive_dirk-museum/node_modules/gulp-nunjucks-render/node_modules/readable-stream/lib/_stream_writable.js:194:11)