Add two convenience fns

[codecov[bot]]

Codecov Report

Merging #25 (44352b5) into master (82e959c) will decrease coverage by 0.05%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #25      +/-   ##
==========================================
- Coverage   99.68%   99.63%   -0.06%     
==========================================
  Files          45       51       +6     
  Lines       16428    21665    +5237     
==========================================
+ Hits        16377    21585    +5208     
- Misses         51       80      +29     

Impacted Files	Coverage Δ
src/internet/ip.rs	100.00% <100.00%> (ø)
src/packet_slicing.rs	100.00% <100.00%> (ø)
tests/internet/ip.rs	99.59% <100.00%> (+0.07%)	:arrow_up:
tests/packet_slicing/mod.rs	98.78% <100.00%> (+0.40%)	:arrow_up:
tests/packet_compositions/mod.rs	96.98% <0.00%> (-0.95%)	:arrow_down:
tests/packet_filter/mod.rs	99.05% <0.00%> (-0.95%)	:arrow_down:
tests/unit-tests.rs	97.79% <0.00%> (-0.72%)	:arrow_down:
src/transport/tcp.rs	99.88% <0.00%> (-0.01%)	:arrow_down:
src/packet_filter.rs	100.00% <0.00%> (ø)
... and 15 more

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