Exercise 4-7

# 3)
unlist(list(list(1, 2), sd))

## [[1]]
## [1] 1
## 
## [[2]]
## [1] 2
## 
## [[3]]
## function (x, na.rm = FALSE) 
## sqrt(var(if (is.vector(x) || is.factor(x)) x else as.double(x), 
##     na.rm = na.rm))
## <bytecode: 0x55aa110f6ff8>
## <environment: namespace:stats>

list(1, 2, sd)

## [[1]]
## [1] 1
## 
## [[2]]
## [1] 2
## 
## [[3]]
## function (x, na.rm = FALSE) 
## sqrt(var(if (is.vector(x) || is.factor(x)) x else as.double(x), 
##     na.rm = na.rm))
## <bytecode: 0x55aa110f6ff8>
## <environment: namespace:stats>