arithmetic

s_term:=

expressions | sprefixed

expressions | s_term / spowerdiv

expressions | s_term % spowermod

sproduct:=

expressions | s_term

expressions | s_term * sproduct_listmul

sproduct_list:=

expressions | s_term ( * s_term)*

ssubtraction:=

expressions | sproduct

expressions | ssubtraction - sproductsub

ssum:=

expressions | ssubtraction

expressions | ssubtraction + ssum_listadd

ssum_list:=

expressions | ssubtraction ( + ssubtraction)*