It's Keykat's turn to do some cleaning for a change. I hope she can do a good job, as there's dust everywhere and the floors are dirty.
The ~서 form is commonly used to mean "because," but it also has another common usage when combined with action verbs to mean "and then." This form can be used to mean that the second action (whatever is used after this form) happens immediately after the first action (whatever this form is attached to).
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