When salyut 7 – ve-4 – eva 1 is the spacecraft, what is the duration?
CREATE TABLE "spacewalks" (
  "spacecraft" text,
  "spacewalker" text,
  "start_utc" text,
  "end_utc" text,
  "duration" text,
  "comments" text
);
SELECT "duration" FROM "spacewalks" WHERE "spacecraft"='Salyut 7 – VE-4 – EVA 1';