Feature engineering: 'if yesterday exists, set lead variable = 1' + 'if tomorrow exists, set lag variable = 1'

[pathos]

Scenario:
Let's say x = 1 on 2000 Jan 15.
So calendar_date column with 2000-01-15 value

Expected result:
Then x_lead := 1 on 2000 Jan 14
and x_lag := 1 on 2000 Jan 16

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First, how do I detect that 2000-01-14 exists in the calendar_date column?
Then, how would I df |> mutate(x_lead = 1) at the 2000-01-14 row?

[Yarnabrina]

Use case_when, with condition being absolute of date difference being 1.