Add struct definition #1858

Job	Run time
Performance Benchmarks	4m 0s
Check Minimum Rust Version for protocols library	29s
Check Formatting	7s
Type-check, lint & format Python files	9s
Unit Tests (nightly)	1m 31s
Unit Tests (beta)	1m 20s
Clippy Lints	30s
Unit Tests (stable)	1m 27s
	9m 33s

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