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Primary Constructors: Collection Expressions: Spread Operator

int[] row0 = [1, 2, 3];
int[] row1 = [4, 5, 6]; 
int[] row2 = [7, 8, 9]; 
int[] single = [.. row0, .. row1, .. row2];

ref readonly parameters: like IN keyword
default lambda paramaters: define default parameter for lambda function
alias any type: not just named types but tuples, etc
Inline arrays: like a struct
experimental attribute: for a compiler warning