groovy.lang.MissingMethodException: No signature of method

Hello,

I want to create a variable which changes a data format to be in HH / MM / SS.  

but i have a message error :

Caught: groovy.lang.MissingMethodException: No signature of method: main.col() is applicable for argument types: (java.lang.String) values: [dureeAppel]
Possible solutions: run(), run(), any(), any(groovy.lang.Closure), is(java.lang.Object), use([Ljava.lang.Object;)
groovy.lang.MissingMethodException: No signature of method: main.col() is applicable for argument types: (java.lang.String) values: [dureeAppel]
Possible solutions: run(), run(), any(), any(groovy.lang.Closure), is(java.lang.Object), use([Ljava.lang.Object;)
	at main.run(main.groovy:5)

What am I doing wrong?

thank you