set.seed(123)
x1 <- runif(10)
x2 <- as.character(sample(c(1:20), 10, replace = TRUE))
x2_num_test <- is_numable(x2)
x2_num_test
x3 <- sample(LETTERS, 10, replace = TRUE)
x3_num_test <- is_numable(x3)
x3_num_test
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