input: 
  def linearSearch(arr, value):
    """
    Performs a linear search on the given array to find the index of the specified value.
    If the value is found, it returns the index; otherwise, it returns -1.
    
    >>> linearSearch([5, 3, 7, 2], 7)
    2
    >>> linearSearch([5, 3, 7, 2], 10)
    -1
    """
  
output:     for i in range(len(arr)):
          if arr[i] == value:
              return i
      return -1