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SECD

SECD = state, environment, control, dump​

DEFINE = DECLARE + SET

[!NOTE] altough the environment, representing an E, is formed at routine start and destroyed at routine conclusion, closure function as intended since it starts with the environment of the parent procedure

READ
    read on value from C onto S

LOAD
    read one value from .data onto S

ASSERT
    if S(-1) is falsy, print S(0) and exit

PRINT
    pop S(0), and print the output

SET
    read one word from C, saves the key E[word] to the value S(0), popping S(0)

GET
    read one word from C, finds the value of E[word], leaves the value on S

DECLARE
    read two word from C, create a new entry in E with the key E[word1], the type defined by word2, the value `null`

DEFINE
    read two words from C, create a new entry in E with the key E[word1], the type defined by word2, the value popped from S(0)