Function interp_sys_getenv 

fn interp_sys_getenv(
    args: &[RValue],
    named: &[(String, RValue)],
    context: &BuiltinContext<'_>,
) -> Result<RValue, RError>

Get environment variable(s) from the interpreter’s environment.

@param x character vector of variable names. If missing, returns all env vars as a named character vector. @param unset character scalar: value to return for unset variables (default “”) @param names logical: if TRUE (default), set names on the result @return character vector with the variable values