ExprASTResult is a Top level function AST traversal if an arithmetic runtime error occurs, a panic exception is thrown.

Float64ToStr float64 -> string.

Top level function Analytical expression and execution err is not nil if an error occurs (including arithmetic runtime errors).

the integer power of a number.

RegFunction is Top level function register a new function to use in expressions name: be register function name.

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e.g.

e.g.

enum "RadianMode", "AngleMode".