code: def from_string(string):
          
          mnemonics = {
              # Arithmetic Instructions
              "add": ReilMnemonic.ADD,
              "sub": ReilMnemonic.SUB,
              "mul": ReilMnemonic.MUL,
              "div": ReilMnemonic.DIV,
              "mod": ReilMnemonic.MOD,
              "bsh": ReilMnemonic.BSH,
  
              # Bitwise Instructions
              "and": ReilMnemonic.AND,
              "or":  ReilMnemonic.OR,
              "xor": ReilMnemonic.XOR,
  
              # Data Transfer Instructions
              "ldm": ReilMnemonic.LDM,
              "stm": ReilMnemonic.STM,
              "str": ReilMnemonic.STR,
  
              # Conditional Instructions
              "bisz": ReilMnemonic.BISZ,
              "jcc":  ReilMnemonic.JCC,
  
              # Other Instructions
              "unkn":  ReilMnemonic.UNKN,
              "undef": ReilMnemonic.UNDEF,
              "nop":   ReilMnemonic.NOP,
  
              # Added Instructions
              "sext": ReilMnemonic.SEXT,
              "sdiv": ReilMnemonic.SDIV,
              "smod": ReilMnemonic.SMOD,
              "smul": ReilMnemonic.SMUL,
          }
  
          return mnemonics[string]
docs: Return the mnemonic represented by the given string.