This function loads the `U.1` dataset into R.
     
    
    Usage
    load_U_1(filepath = NULL)
 
    
    Arguments
- filepath
- (optional) Path to the downloaded `.Rdata` file.
If `NULL`, the file will be downloaded automatically. 
 
    
    Value
    The loaded dataset.
     
    
    Examples
    if (FALSE) { # \dontrun{
U.1 <- load_U_1()
} # }