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For example,

         >>> colors[3]
              'pink'
         >>> colors[-2]
              'white'
        Lists are mutable, so we can replace an item in a list with another item. For example,

         >>> colors[3]='yellow'
              colors
         >>> ['red', 'green', 'blue', 'yellow', 'orange', 'white', 'black']
        7.1.1 List Derived from a String
        Given a string as an argument, the list() function returns a list. For example,

         >>> vowels = 'aeiou'
         >>> list(vowels)
              ['a', 'e', 'i', 'o', 'u']
        7.1.2 Length of a list: len()
        We can apply the len() function to find the number of elements in a list. For example,

         >>> len(colors)
         >>> 7
        7.1.3 Slicing

        We can use slicing for accessing a subsequence of elements in a list. The following syntax is used for specifying a slice:

        <start>:<finish> [:<step>]
        Note that the step is optional. Below we give some examples of slicing,
         >>> colors[3:6]
              ['yellow', 'orange', 'white']
        The slice [3:6] yields a list comprising the elements colors[3], colors[4], and colors[5], but not
        colors[6].
        The slice [:3] yields the list comprising the list elements up to index 3 (excluding the element at index 3). For example,

         >>> colors[:3]
              ['red', 'green', 'blue']
        Note that colors[-1] and colors[6] refer to the same position in list colors. So, the slice [1: -1] yields the

        list comprising the list elements colors[1], colors[2], …, colors[5] excluding colors[6].
         >>> colors[1:-1]
              ['green', 'blue', 'yellow', 'orange', 'white']
        The slice [::2] yields a list,  comprising the alternate elements of the list, because the step size is 2:

         >>> colors[::2]
              ['red', 'blue', 'orange', 'black']
        The slice  [1:7:3] yields a list, comprising the elements beginning at index 1 and up to index 7 (excluding the
        element at index 7), in steps of size 3. Thus, the expression colors[1:7:3] yields a list comprising the elements
        colors[1] and colors[4]:
         >>> colors[1:7:3]
              ['green', 'orange']













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