Simplify code complexity

[llrs-roche]

Pull Request

Fixes #295

                         name cyclocomp
16         extract_occurrence        16
12        extract_assign_call        15
39 move_functions_after_arrow        10
36                 lang2calls         7
6                      c.qenv         6
20       fix_shifted_comments         6

Reduced in half the extract_occurrence complexity by moving a branch of code to the function extract_assign_call.
extract_dependency() was simplified to be out of the top 6 too.

Setting to draft as it might need more work to make it readable

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[llrs-roche]

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