Function rewrite_in_terms_of_projection 

fn rewrite_in_terms_of_projection(
    expr: Expr,
    proj_exprs: Vec<Expr>,
    input: &LogicalPlan,
) -> Result<Expr>

Rewrites a sort expression in terms of the output of the previous LogicalPlan

Example:

Given an input expression such as col(a) + col(b) + col(c)

into col(a) + col("b + c")

Remember that:

1. given a projection with exprs: [a, b + c]
2. t produces an output schema with two columns “a”, “b + c”