input: Write a python function to group a list of strings by their first character.
  assert groupStrings(['apple', 'elephant', 'ball', 'cat']) == {'a': ['apple'], 'e': ['elephant'], 'b': ['ball'], 'c': ['cat']}
  assert groupStrings(['dog', 'deer', 'cat', 'cow']) == {'d': ['dog', 'deer'], 'c': ['cat', 'cow']}
  assert groupStrings(['banana', 'berry', 'cherry', 'carrot']) == {'b': ['banana', 'berry'], 'c': ['cherry', 'carrot']}
output: def groupStrings(strings):
      grouped = {}
      for string in strings:
          first_char = string[0]
          if first_char not in grouped:
              grouped[first_char] = []
          grouped[first_char].append(string)
      return grouped