there is a big amount of code that changes field_A value in form via workflow rule.

and there are about ten  other fields where this " big amount of code" exists and repeats.

if a value in one of  other fields changes - changes value in  field_A value

because in workflow rules of each  other fields  there is " big amount of code"

sometimes it needs to make changes in " big amount of code".

so that it needs to change same codes in workflow rules of every ten  other fields 

it is too complex.

how can i make a one-word-function, so that

- there is one place to make changes in " big amount of code"

- in workflow rules of every ten  other fields  i can invoke  one-word-function to change value of  field_A value