root level accept/produce params

[ubogdan]

Describe the PR
add root level @accept @produce to help on reducing boilerplate.

Relation issue
#887

Additional context
None.

[codecov]

Codecov Report

Merging #1011 (6fe3a11) into master (f9645be) will increase coverage by 0.04%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1011      +/-   ##
==========================================
+ Coverage   93.21%   93.25%   +0.04%     
==========================================
  Files           7        7              
  Lines        1931     1943      +12     
==========================================
+ Hits         1800     1812      +12     
  Misses         73       73              
  Partials       58       58              

Impacted Files	Coverage Δ
operation.go	95.10% <100.00%> (ø)
parser.go	93.48% <100.00%> (+0.08%)	⬆️

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[ubogdan]

@sdghchj, please give me a hand with a review here.