def vowel_count(list_of_strings):
  """Returns a dictionary of vowel counts for the given list of strings.

  Args:
    list_of_strings: A list of strings.

  Returns:
    A dictionary, keyed on the five vowels a, e, i, o, and u. The value for each
    should be the total number of entries in the list which contain at least a
    single copy of that vowel.
  """

  vowel_counts = {}
  for vowel in ['a', 'e', 'i', 'o', 'u']:
    vowel_counts[vowel] = 0

  for string in list_of_strings:
    for vowel in ['a', 'e', 'i', 'o', 'u']:
      if vowel in string:
        vowel_counts[vowel] += 1

  return vowel_counts