Function csv_calc 

pub fn csv_calc(query: &str) -> String

Preview, filter, select columns, count/sum/group-by CSV data — instant, no Python.

Commands (all accept either a file path or inline CSV rows after the command): preview <file> — show first 10 rows with column headers head N <file> — show first N rows cols <file> — list column names and indices select <col1,col2> <file> — select specific columns filter <col> <op> <val> <file> — filter rows (ops: = != > < >= <=) count <file> — count rows sum <col> <file> — sum a numeric column avg <col> <file> — average a numeric column groupby <col> <file> — group-by column and count sort <col> [asc|desc] <file> — sort by column