Function show 

pub fn show(
    value: Option<&Value>,
    data: &Value,
    path: &[String],
    row_keys: &[usize],
) -> bool

Whether a design.show value shows its field. The value resolves like a conditional parameter: a condition map selects its value, a ternary its branch and a condition expression that parses completely its value; any other string and any other value is a literal. Only a value that resolves to false hides the field, so a missing value, null, a condition map that selects nothing and a literal string show it. path is the field’s data path, row keys included, and row_keys the positions of the row keys in it.