h2o.rep_len performs just as rep does. It replicates the values in
x in the H2O backend.
    
     
    h2o.rep_len(x, length.out)
    
    Arguments
    
    
    
      | x | an H2O frame | 
    
      | length.out | non negative integer. The desired length of the output
vector. | 
    
    
    Value
    Creates an H2OFrame of the same type as x